\input pstfig
\hskip 2cm
$
\setcoorunit{4}{1}
\psset{yunit=0.3\psxunit}
\psset{xunit=1.2\psxunit}
\drawaxes{-1.6}{3.1}{-5.7}{6}
\uput[-50](0,0){\scriptstyle O}
\markxlabel{-1}{-\pi}{1.5em}
\markxlabel{1}{\vphantom{2}\pi}{1em}
\markxlabel{2}{2\pi}{1.5em}
\psplot{-0.94}{-0.06}{1/tan(x*\pinum)}
\psplot{0.06}{0.94}{1/tan(x*\pinum)}
\psplot{1.06}{1.94}{1/tan(x*\pinum)}
\dashline\thinline
\psline(-1,5.3)(-1,-5.3)
\psline( 0,5.3)( 0,-5.3)
\psline( 1,5.3)( 1,-5.3)
\psline( 2,5.3)( 2,-5.3)
$
\bye
